What if a user is in a car when they go through a geofence? Will that data be captured, even if the user is going 60+MPH?

Geofences trigger even for users in motion - the dwell time on the “Visited” event in analytics may be quite low in this case though because they have spent such little time within the geofence.

Note that because the OS sometimes delays geographic checks to balance battery life, the triggering is not guaranteed and geofence events are slightly more likely to be missed when the geofence is smaller or the user is traveling fast.